import java.util.Scanner;
	

public class Main{
	
	
	public static void main(String args[])throws Exception{
		
		Scanner sc = new Scanner(System.in);
		int W = sc.nextInt();
		int H = sc.nextInt();
		String c = sc.next();
		char C = c.charAt(0);
		char notC = (char) ('B' + 'W' - C);
		for(int i=0;i<H;i++){
			for(int j=0;j<W;j++){
				if((i+j)%2==0){
					System.out.print(C);
				}else{
					System.out.print(notC);
				}
			}
			System.out.println();
		}
		
		
	}
}